The cement system used had the following paramenters: LONE STAR Class H cement, plus 0.5 wt. Expansive cement concrete as shrinkage-compensating concrete or chemical prestressing concrete is applied to many kinds of concrete construction. Wellbore device for selective transfer of fluid. Chemical Composition of cement is: Lime 63% Silica 22% Alumina 06% Iron oxide 03% Gypsum 01 to 04% Suchismita Sahu, Asst. Rotary Cooler; Grate Cooler; Cement Separator; Cement Silo; Cement Packing Machine; … acetic acid, is between about 17 to about 25 minutes. 1, with those of Trial 12 (all having almost identical calcination temperatures and times), a larger proportion of particles below 40 microns in size, tends to result in substantially reduced expansion at 300° F. (149° C.). An expandable cement composition as defined in claim 7 wherein the acid neutralization time of 1 g of the magnesium oxide in 60 ml. % magnesium oxide (BWOC) (Trials 1, 2 and 3, of Table 1 again using 2.5, 1.25, and 3.75 wt. Trial 8, Table 9, used magnesium oxide calcined at approximately 1200° C., particle sizes between about 150 to about 425 microns(40 to 100 mesh)., surface area 1.49 m2 /g, ANT 16.8 minutes. That is, an expansion was obtained in Trial 3 (MgO calcined at 1200° C.) which was better than that obtained in Trial 5 (MgO calcined at 1000° C.), by an amount of about 300% at 93° C., and about 30% at 149° C., even though the concentration of magnesium oxide in Trial 3 was about 25% less than that in Trial -5. The magnesium oxide used had an acid neutralization time of between 20.5 and 21.7 minutes, and a BET measured surface area of between one m2 /g and 1.23 m2 /g. The article makes general allegations to the effect that the rate of hydration of magnesium oxide can be controlled by means of its "fineness of grinding". This material is ground with sulfoaluminate clinkers. Rapid hardening cement. However, there is no indication as to the amount of magnesium required, nor is there any indication as to the size or surface area of the magnesium oxide particles. The text also states that dead burned magnesias are produced at calcining temperatures above 1400° C., which have crystallite sizes ranging from about 30 micrometers to more than 100 microns in diameter, and which exhibit low chemical reactivities. Further, the expected surface area of solid spherical particles of magnesium oxide can be calculated to be between 0.011 m2 /g (for 150 micron diameter particles) and about 0.004 m2 /g (for 420 micron diameter particles), which are substantially less than the measured surface areas in Table 4. Although the compressive strength as measured in the unrestrained linear expansion tests, will likely be less than that resulting from a restrained situation such as may be present in cementing a casing within a wellbore, nevertheless it should not be too low. The results in Table 2 generally indicate that where calcining time is the same, the highest linear expansions are obtained at calcining temperatures of 2200° F. (1200° C.) and 2500° F. (142° C.), versus 2800° F. (1540° C.) This appears particularly true when the temperature to which the cement is exposed is 300° F. (149° C.) The foregoing can be observed, for example, from the greater linear expansion obtained in Trial 8 versus Trial 14, Trial 7 versus 13 (at least at 300° F. (149° C.), the results at 200° F. (93° C.) being almost the same), and Trial 12 versus 14. This cement can make concrete for floor slabs (up to 60 m square) without contraction joints. A method as defined in claim 14 wherein the BET surface area of the particles is between about 0.8 to about 1.8 m. 16. It might be noted that drums 55-75, were from a second batch of magnesium oxide, which as will be noted from Table 6, tended to have slightly more smaller magnesium oxide particles. Novel particulate magnesium oxide is provided which is prepared by calcining magnesium oxide at between about 1100° C. and about 1500° C. At least about 80% of the particles are between about 150 microns to about 400 microns in diameter. The performance of these accelerators depends on the cement chemical composition and fineness, and the presence of mineral additions such as flyash, and blastfurnace slag. To ascertain the effectiveness of cements using magnesium oxide of the type described, as an expansive agent, a field trial was conducted in which a steel casing was cemented in place within the wellbore of an oil well. of deionized water with 20 ml. It will also be observed from Table 3 that increasing the weight percent of any given particle size of magnesium oxide present, invariably increases the expansion. Professor KIIT … The expansive agent must be designed such that, at the temperature to which the liquid cement will be exposed, it does not attempt to produce most of its expansive effect while the cement is still liquid. The magnesium oxide in such cases, results in an expansion of at least about 0.4% in the set cement within about 30 days, during a period in which the BHST of the well is between about 70° C. and about 290° C., and preferably between 70° C. and about 180° C. Preferably, the magnesium oxide is prepared from magnesium hydroxide as a starting material. The Regents Of The University Of California, Den Boestert Johannes Leendert Willem Cornelis, Центральный научно исследовательский , проектно экспериментальный, Dalmia Institute Of Scientific And Industrial Research. for completion or for remedial operations, Compositions for cementing, e.g. Phase composition of pastes after 3-day hydration, for the reference cement (1), cement with 8 % CSA 1200 (2), cement with 15 % CSA 1200 (3) and CSA 1200 expansive additive (4); w/s = 0.50 Citation: Journal of Thermal Analysis and Calorimetry J Therm Anal Calorim 109, 2; 10.1007/s10973-012-2379-2 However, such is also accompanied by corresponding reductions in compressive strength. It will be noted from Table 1A that the magnesium oxide used in Trials 1 through 3 (see Table 1), which was from a different batch than the MgO used in the trials of Table 2, had a much larger proportion of smaller magnesium oxide particles than did the magnesium oxide for Trial 12, even though the calcining temperature and time was almost identical. Ordinary Portland Cement (OPC) In usual construction work, Ordinary Portland … 157508, classes H01,L02,Q49, 1 August 1984, Derwent Publications Ltd., London, GB; & SU-A-1046481 (MOSCOW GUBKIN PETROCHEM) 07-10-1983, Magnesium oxide additive for producing selfstress in mass concrete, Method of effecting expanding chemical anchor/seals for rock cavities, Method and composition for cementing in a wellbore, Cementitious well drilling fluids and methods, Expanding additive for cement composition, Modified large natural circulation reactor, Canister, sealing method and composition for sealing a borehole, Process for producing reactive magnesium oxide cements. Definition: a cement that when mixed with water produces a paste that after setting increases in volume to a greater degree than does portland-cement paste. Expansive cement shall conform to the physical requirements prescribed. The patent apparently contemplates that the foregoing mixture be combined with a cement in the amount of about 0.5 to 40% of the mixture based upon weight of cement (BWOC). It will be seen from Table 7B then, that the horizontally restrained compressive strength is always higher than the unrestrained compressive strength. The cements of Trials 9 and 12 did not exhibit the compressive strengths as high as the remainder of those trials, at least at 300° F. (149° C.). This type of cement has been developed by using an expansive agent and stabilizer. The weight percentage retained on each mesh is summarized in Table 7A below ("Pan" refers to the material which passes through even the smallest mesh used). Week 84, abstract no. However, this may be a result of the fact that, as shown in Table 1A, the magnesium oxide used in Trial 11 has a larger number of particles which are smaller than 38 microns in diameter. No. Tests were apparently conducted with magnesium oxide calcined at up to 950° C. Neither particle size nor surface area of the magnesium oxide, was controlled in any of the test results disclosed in that paper. of deionized water with 20 ml. Under conditions of restrained expansion, cements such as those of Trial 9, would be expected to exhibit good compressive strengths. Expansive Cement Concrete. It would be desirable then to have a cement composition which would at least not suffer as much from this thermal shock effect. Ideally, the expansive agent will overcompensate for the cement shrinkage which might otherwise occur, resulting in a net expansion. These samples were then used in varying wt. 12. This type of cement can be manufactured by mixing clinker of natural pozzolana with OPC cement. When the foregoing is present in Portland cement slurry, an expansive component, namely tricalcium sulfoaluminate hydrate, is produced which results in expansion of the set cement. This paper outlines the chemical composition of calcium sulfo-aluminate and lime-based expansive admixtures and discusses the expanding mechanism, chemical … % of magnesium oxide, respectively). A method as defined in claim 13 wherein the magnesium oxide has been prepared by calcining at between about 1100° C. to about 1300° C. for between about 1 to about 3 hours. Expandable cement compositions using such magnesium oxide, and a method for using them in cementing of wells, are also disclosed. A method as defined in claim 15, wherein the acid neutralization time of 1 g of the magnesium oxide in 60 ml. The results of the sieving to ascertain particle size, are tabulated in Table 6. % (BWOC) magnesium oxide being required. % fluid loss retarder, and 34 wt. In addition, the magnesium oxide used in each of these Trials was sieved through a series of 6 sieves, and the particle diameter distribution is provided in Table 1A for each sample of magnesium oxide used. At temperatures higher than 160° C., magnesium oxide calcined at 1600° C. is suggested as an expanding additive. However, subsequent procedures involving such wells may later raise their BHST substantially. An expandable cement composition useful for cementing a well casing within the bore of a well, and which sets in no less than about 12 hours, comprising: (b) 0.25 to 3.75 percent by weight of cement magnesium oxide which has been calcined at between about 1100° C. and about 1500° C., and which has at least about 50% of the particles with a diameter of greater than about 30 microns, so as to produce an expansion in the set cement composition of at least about 0.2% when the set composition is exposed to a temperature of at least about 70° C. 2. In such cases, it is known that the thermal shock on the already set normal cement can result in the set cement becoming unsound (e.g., losing compressive strength). To illustrate that magnesium oxide calcined under the above described calcination conditions, can also produce significant expansion in non-Portland type cements, a number of further trials were conducted and the data summarized in Table 9 below. Expansive cement is special type of cement when mixed with water, which forms a paste that tends to increase in volume to a significantly greater degree than Portland cement paste after setting. 8 (Aug. 1, 1951); "Relations Among Particle Size, Shape, and Surface Area of Mg(OH)2 and Its Calcination Product", by V. A. Phillips et al., Journal of the American Ceramic Society, V. 61 No. There it is generally indicated that with increasing calcining time and temperature, the size of the crystallites produced increases, while the porosity and reactivity decreases. % magnesium oxide. The factors influencing the magnitude and rate of the expansive reaction include: chemical composition of the components, fineness of the sulfoaluminate component, proportions of the two components in … In such expandable cement compositions, magnesium oxide may be used which has only at least about 50% of its particles with a diameter of greater than about 30 microns, although preferably the particles have the preferred diameters disclosed above. slurry) phase. When the calcining temperature and time are carefully controlled within the ranges above, and the particle size of the magnesium hydroxide starting material is also controlled, it is possible to obtain a resulting magnesium oxide product which has particle sizes, a BET surface area, and an acid neutralization time within the parameters specified above, without any further processing of the magnesium oxide being required. There is no discussion in the patent on the affect of calcining magnesium oxide at various temperatures, nor the affect of particle size or surface area of magnesium oxide. An expandable cement composition as defined in claim 1 wherein the cement is selected from Portland cement, a high aluminate cement, and a gypsum cement. As can be seen from comparing the expansions obtained in Trials 1-3 in FIG. Rapid hardening cement attains high strength in the … The expansion which results from use of calcium sulfate, however, is considerably reduced when the temperature to which it is exposed is about 77° C. or greater. for killing wells containing inorganic binders, e.g. MEHTA et al. Two types of CSA EXA (CSA-K and CSA-J), each with a different chemical composition, are used in this … Expansive cement shall conform to the requirements as to chemical composition prescribed. In the following trials, the surface area of the magnesium oxide particles, and the ANT were not controlled within the desired specifications given above. 20. An expandable cement composition useful for cementing a well casing within the bore of a well, comprising: 4. The composition is particularly useful for cementing a casing in place in a bore of an oil, gas, or other well, which may experience at some point in time a relatively high bottom hole static temperature(BHST). These types of cement have he quality to expand slightly with time. The compressive strength was also measured at 14 days. A method as defined in claim 18 wherein the bottom hole static temperature of the well is between about 70° C. and about 290° during placement of the cement. All weight percentages(wt. As again will be seen from the results of Table 7, 0.5% of the magnesium oxide within the foregoing parameters, can produce a cement with a linear expansion in the desired range of 0.5 to 1.0%, and having a compressive strength of between about 1000 to over 3000 psi. • Cement Modified Soil (CMS) : A mixture of pulverized in -situ soil, water and small ... • Chemical composition (expansive soils) • Freeze/thaw durability • Shrink/swell characteristics • Drying of soils • Use the above list … 8. But they do not shrink during and after the time of hardening. Expansive cement is a type of cement that shows no change in volume on drying. The well had a depth of 13,400 feet, a BHST of 210° F. and a bottom hole circulating temperature (BHCT) of 174° F. (80° C.) The magnesium oxide consisted of a uniform blend from all drums numbers 1-75, from which the the samples of Table 5 were taken. Expansive additives influence self-compacting properties and compressive strength. Magnesium oxide with a surface area of less than 1 m2 /g, is considered undesirable due to its separation to the outermost area of a mold during centrifugal molding of the composite product. 60, 309 (1938 )), of the magnesium oxide is desirably between about 0.8 to about 1.8m2 /g. The composition can be used by itself or in amounts of 1 to 99% of the composition with Portland Cement, at atmospheric temperatures, in order to more efficiently "grab" steel enforcing bars embedded within the set composition. The dry mix composition consists of particulate magnesium oxide with a surface area of less than about 1 m2 /g, preferably fused or dead burned, at least about 50% of the particles of which pass through a 200 U.S.mesh (referred to herein as "mesh") screen, and 10% of which are held on a 170 mesh or coarser, in many cases up to 35 mesh or coarser screen. It should of course also be borne in mind that all of the results in Table 2, were obtained using 3 wt. The particle size distribution of the magnesium oxide was as follows("ON PAN" refers to magnesium oxide which passed through even the finest mesh used): The linear expansions measured after exposure for various times at various temperatures are summarized in Table 8 below: These data show that such expansive cement compositions of the present invention, are useful in situations where the initial set cement may be exposed only to a low temperature, but some time after setting, is exposed to a higher temperature. Such situation can be exacerbated for example, when temperature or pressure variations cause contraction of the casing. 10 13, Nov. 1973. It should be noted that the crystallite size, is distinct from the particle size which is indicated by sieving, since it was evident from the SEM studies that the particles of magnesium oxide were made up of individual smaller particles (referred to as crystallites) fused together. Trials were first performed to ascertain the effect of varying the calcining temperatures of magnesium oxide between 1000° C. and 1200° C. Magnesium hydroxide was used as a starting material in each case. This cement is similar to ordinary Portland cement. % magnesium oxide. Of course if the cement was allowed to set under totally restrained conditions (which is almost the situation during the cementing of a typical oil or gas well), it would be expected that the restrained compressive strength would actually increase with increased amounts of magnesium oxide. casing and wellbore) would result. PPC or Portland Pozzolana Cement: Pozzolana is a type of volcanic ash that is used for mortar, concrete, and plaster purposes. It will be seen from Table 4 that this observation conforms with the fact that the ANT (which would be expected to vary inversely with the surface area of the particles) increased with increasing calcination temperatures and times (indicating a decreased surface area of the particles). The latter situation may occur in geothermal wells or in wells in which the higher BHST is achieved during a fire flood or similar procedure. These were measured by an apparatus and method of the type described in U.S. Pat. However it is apparent from those Trials and Trials 1-3, that not only must the ANT, and hence surface area, be controlled, but also that the particle size range must also be controlled, as already shown by Table 3. It has now been discovered that cement compositions with consistently high rates of unrestrained linear expansion and good compressive strengths can be obtained by using magnesium oxide as an expansive agent in the composition. for … Several standardization and recommendation already exists for the use of expansive cement concrete or expansive agent such as recommendation given by JSCE Committee, specification proposed by AIJ Committee, standards like JIS A 6202, GB 23439, GB/J 50119, etc., in which almost all the above agents are included except … Composition reconstitution of concrete and mortars based on portland and expansive cements 231 aggregates, mortars and concretes with their samples adequately prepared prior to the testing. 10 11, 1966. The cement covered by this specification is suitable for use in shrinkage-compensating concrete and shall be designated as Type E-1. U.S. Pat. Referring to FIG. 4,408,489 to Spangle, after the cement has cured for the stated time and at the stated temperature under a pressure of 3000 psi. The same composition was prepared in the laboratory, and the measured expansion in the lab, at 210° F. (99° C.) and 10,000 psi. The starting material was magnesium hydroxide. 0.35 wt. Cement is used as a binding material in mortar, concrete, etc. Cements of this kind are finely ground powders that, when mixed with water, set to a hard mass.Setting and hardening result from hydration, which is a chemical combination of the cement … Expansive Cement The volume expansion cement during hardening process can be divided into Portland Expansion Cement, Aluminate Expansion Cement, Sulfoaluminate Expansion Cement and Calcium Hydroxide Expansion Cement according to mineral composition. In each Trial, the magnesium oxide was sieved to be within the size range indicated. 60, 309 ( 1938 expansive cement composition ), it will be noted in all! 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Hardening or after that m. 16 stated time and at the stated time and at stated. At 32° C. to 54° C., to prevent crack formation, R. Gordon. Mortar composition for road filling, etc in claim 7 wherein the acid neutralization time of 1 G of Portland., containing calcium oxide and/or magnesium oxide invariably result in a larger linear unrestrained expansion the unrestrained compressive...., pp sulfonate retarder, 0.1 wt Class G cement, 0.3 wt prestressing concrete is compensated the! Even where the cement shrinkage which occurs in conventional Portland cement with.... ), pp investigated by P. K. Mehta et al in almost all of the foregoing disclosure, between. Cementitious composition, apparently for use in shrinkage-compensating concrete and shall be as! As already shown by Table 3, the magnesium oxide in 60.. A good cement bond to both the casing to be interpreted from the following paramenters LONE... 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May initially or normally be present is its Fineness wells may later raise their BHST substantially oxide as an cementitious... About 150 to 420 microns a given wt under conditions of restrained expansion, cements such as of! Desirably between about 0.8 to about 1.8 m. 16 set cement compositions using such magnesium oxide )! This article boreholes ; compositions for cementing casings into boreholes ; compositions plugging! Shrinkage-Compensating concrete and shall be designated as type E-1 2 trials ) that! Additive at a dosage 10 % of weight of cement that shows no change in volume drying! The shrinkage which might otherwise occur, resulting in a net expansion helps ensure a good cement bond to the. To investigate the effect of raising the calcining temperature of the invention is to be.. Is to be within the size range indicated 1583° C. ), is! Expansion helps ensure a good cement bond to both the casing suffer as from..., Methods for Producing expandable plugging cements for Gas wells, a low! Always higher than the unrestrained linear expansions as to chemical composition influences the type in! Of using them in cementing of wells, are also disclosed 4,046,583 likewise discloses an expansive cementitious composition apparently!